public class Test {
    public static void main(String[] args) {
        SingleLinkedList List = new SingleLinkedList();
        List.addLast(1);
        List.addFirst(2);
        List.addFirst(3);
        List.addFirst(4);
        List.addFirst(5);
        List.addFirst(6);
        List.addLast(7);
        List.display();
        System.out.println(List.addIndex(0,1));
    }
}
